Polymers of carbon monoxide and olefins generally referred to as polyketones are well known in the art. Such polymers are disclosed in, for example U.S. Pat. Nos. 2,495,286; 3,694,412; and U.K. 1,081,304 which are herein incorporated by reference.
Of particular interest among polyketone polymers, is the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. This type of polymers is disclosed in European Patent Applications such as Nos. 121,965; 181,014; 213,671; and 257,663 which are herein incorporated by reference. Additionally, this class of polymers is disclosed in numerous U.S. patents assigned to Shell Oil Company, exemplified by U.S. Pat. Nos. 4,880,865 and 4,822,871 which are herein incorporated by reference.
Polyketone polymers have relatively high molecular weights and are used in the production of shaped articles, such as containers for food and drink and parts for the automotive industry, which are produced by processing the polyketone polymer according to well known methods.
It is known that polyketone polymers have stability problems. See for example R. Gooden, et al, Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 24, 3191-3199 (1986) and R. Gooden, et al., New Trends in the Photochemistry of Polymers, Applied Science p. 159 (1985).
These stability problems include ultraviolet (UV), melt stability, and heat aging stability, sometimes also referred to as continuous use temperature (CUT). While antioxidants and other additives provide some degree of improvement, it would be of advantage to provide new techniques and materials which yield further improvements in thermal oxidative stability of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. For most polymers including polyketones, thermal oxidative degradation leads to chain scission, reduction in molecular weight, and loss of physical properties. These adverse effects of oxidative chain scission reactions are undesirable, and continue to present a problem to those of skill in the art. Thus, there continues to exist the need to produce ethylene-CO polymers that have and exhibit superior melt stability properties.
It is a discovery of this invention that addition of magnesium oxide and alumina to a polyketone polymer composition result in an improvement in the melt stability of the composition.